Strata Analysis Of Maotian Formation In Dejiang Area,Guizhou

Event stratigraphy is a rapidly deposited and rare sedimentary unit in a short period of time,which occurs mainly in relatively slow normal sedimentary settings.The rock types,structures,structures and biological characteristics of event layer and background deposit are significantly different.On the basis of many previous studies,the paper made full use of the outcrop,section records and thin slice analysis data,and studied the sedimentary system and the formation of the formation of the top Cambrian and lower Ordovician Maotian formation in the Dejiang area,Guizhou,through the characteristics of lithology and sedimentary structure.The Maotian formation in the study area is developed in the tidal flat strata of the carbonate platform,and the sedimentary position is located on the edge of the platform,with thick layered microcrystals,muddy grained limestone and deep gray thick layered Oolitic Limestone.The development of horizontal stratification,oblique bedding,Chlamys,panes,bird eyes and other sedimentary structures.The study of event sedimentary geology is mainly based on the identification of the sedimentary structures in the field.In the field of outcrop observation,a series of soft sedimentary deformation structures have been found.The main identification marks are water plastic deformation structure,micro crack,micro fault and ladder like normal fault,micro fold,liquefied vein and discharge structure,liquefied crimp deformation,flame structure,ball pillow structure and so on.Based on the above evidences of sedimentary structures,combined with genetic analysis and identification of seismite marks,the seismic events in the study area are determined.Seismo deposit is a special sedimentary layer with special seismo tectonics and seismo sequence.Therefore,combining with previous studies on seismatite,it is concluded that the vertical sequence of the seismite is more complete and ideal in the Cambrian formation of the Cambrian formation,and the vertical sequence is from the bottom to the bottom.Layer,microfracture material homogeneous layer-ground fissure upper part of the UN seismic layer.The Jiangnan orogenic belt is affected by the snow peak Caledonian cycle,and the orogenic movement is active during the Cambrian period.The accompanying orogenic movement in the southeastern margin of the Yangtze block is bound to cause the tectonic movement to influence a large number of event strata related to it.The discovery of seismo rock in the study area further proves the existence of tectonic orogeny in the early stage of the Yangtze block and Cathaysia Block.From the relation of the characteristics of the seismite(ancient earthquake remnants)with the earthquake magnitude and the seismic intensity,it is preliminarily considered that the seismic magnitude of the seismite in the study area is larger than 6.5 and the earthquake intensity is more than 8 degrees.